1. Technical Field
The present invention relates to a stock feeder and, more particularly, to a stock feeder configured for woodworking equipment and featuring both high dust-tightness and high heat-dissipation efficiency.
2. Description of Related Art
Generally, a stock feeder is used in a woodworking process to feed and hold steady the wood board being worked on. An existing stock feeder typically includes a base disposed on a workbench, a vertical bar inserted in the base, a clamp mounted around the vertical bar, a horizontal bar extending through the clamp and held perpendicular to the vertical bar, a feeding unit pivotally connected to one end of the horizontal bar, and an electrical unit provided on the feeding unit. The bottom portion of the feeding unit is provided with a plurality of feed wheels for holding down a board. The electrical unit has a motor for driving the feed wheels into rotation, a fixing mount provided on the housing of the motor, and a variable-frequency drive (VFD) hung on the fixing mount and configured for changing the rotating speed of the motor.
By operating the handwheel on the horizontal bar and the handwheel on the vertical bar, an operator can move the feeding unit to a predetermined location, so as for the feed wheels to hold down and feed a board to facilitate the woodworking process. While the existing stock feeders are well capable of feeding and holding steady wood boards, the following drawbacks need to be overcome:
1. The VFD, which is directly hung on the exterior of the electrical unit, is both bulky and unsightly. Moreover, although the heat dissipation holes on the VFD housing do provide heat dissipation to some extent, the same holes serve also as a path through which dust, liquid, and like foreign matter can intrude into the internal circuit. Therefore, the externally hung VFD is not suitable for use in a dusty environment and may be easily damaged if so used.
2. The wires to the VFD and to the electrical unit are all exposed and hence have rather low safety coefficients.
3. Both the motor and the VFD in the electrical unit rely on a centrifugal fan to dissipate heat. However, as the fan is fixed to and designed to move synchronously with the rotor of the motor, the rotating speed of the fan will be low if the motor operates at low speed. And if the fan fails to provide forced cooling, heat dissipation efficiency will be reduced significantly.
4. In order to cope with a wood board of uneven thickness, the operator has to adjust the working gap between the feed wheels and the workbench. Nevertheless, the entire feeding unit is so heavy that it may be inadvertently dropped on and thus hit the workbench. Should that happen, the reaction force of the weight of the feed wheel sets will act on the wheel axles, and should that happen again and again, the meshing internal components (e.g., gears) may deform and eventually break.
5. The feed wheels of a conventional stock feeder generally operate on belt transmission. The belts, however, tend to get loose and deform and therefore have a relatively large deformation allowance. As time goes on, the gaps between components will increase, too, which not only causes noise, but also leads to frequent damage, and consequently frequent replacement, of components, incurring a high cost of use.